The present invention relates in general to medical instruments suitable for endoscopic or laproscopic applications, and capable of passing through a trocar or similar device. More specifically, the present invention relates to a novel hydraulically actuated medical instrument suitable for stapling or other desired endoscopic or laproscopic applications.
Surgical instruments, such as staplers, graspers, scissors, coagulators and the like, suitable for endoscopic or laproscopic applications in which the device is inserted through a cannula or trocar, are well known. As described in more detail below, the present invention, in its most preferred embodiment, is directed to an endoscopic stapler particularly suited for minimally invasive surgery for isolating the left atrial appendage on human hearts.
In U.S. Pat. No. 5,306,234, incorporated by reference herein, Dr. W. Dudley Johnson described a minimally invasive procedure for isolating the left atrial appendage of the human heart from the associated atrium. It is known that during atrial fibrillation blood may pool in the left atrial appendage. When blood pools in the atrial appendage, clots may form. Upon the resumption of normal beating, these clots may be ejected from the appendage and enter the blood flow to other parts of the body. If the clots enter the arteries of the brain or heart, stroke or heart attack may result.
In his patent, Dr. Johnson described a procedure for isolating the left atrial appendage without requiring open heart surgery, as was previously used. Specifically, he described entering the chest cavity between selected ribs with a minimally invasive opening or openings, while maintaining the sternum and ribs intact. While this procedure holds great promise, there remains a need for instruments suitable for conveniently and efficiently carrying out this procedure. The present invention provides such an instrument, although it also has aspects and features not limited to the particular procedure described in Dr. Johnson""s patent or to stapling apparatus procedures in general.
Also, endoscopic medical instruments are often of complicated construction, especially when the instrument is articulated to allow the handle and/or end effector to pivot or rotate. Typically, a mechanical linkage extends between the handle and end effector to allow operator actuation of the end effector. When the instrument is of the type that permits articulation, the mechanical linkage must accommodate the articulation. This often results in a design that is relatively complicated, that is costly to manufacture and/or that may still experience limitations regarding the degree or direction of articulation.
The present invention is generally embodied in a medical device of a type suitable for endoscopic or laproscopic procedures and which includes, in one embodiment, an elongated shaft having a proximal end and a distal end, an end effector at the distal end of the elongated shaft, and a handle portion at the proximal end of the elongated shaft. In accordance with the present invention, the end effector is hydraulically actuated and at least one hydraulic fluid flow path extends between the handle portion and the end effector through the elongated shaft.
In accordance with another aspect of the present invention, the medical instrument may include at least one articulation joint at a selected location in or between the handle portion and the end effector. The articulation joint may be located between the elongated shaft and the handle portion, between the elongated shaft and the end effector or elsewhere along the shaft or within the handle or end effector if so desired. More than one articulation joint may be provided to allow greater motion options and to make the instrument particularly well suited to carry out the atrial appendage isolation procedure described above. For that purpose, the end effector is preferably biased in a lateral direction to specially position it for the atrial appendage procedure. It should be noted, however, that although the present invention is described below in terms of a device particularly well suited for the atrial appendage isolation procedure, it includes aspects or features that are not limited to the particular illustrated device or to that particular procedure.
A benefit of the present invention in its preferred embodiment is that the degree and direction of articulation are essentially unlimited. To allow articulation while providing fluid communication between the handle and end effector, at least the portion of the hydraulic fluid flow path in proximity to the articulation joint is flexible. More specifically, the fluid flow path may be flexible along its entire length or may be rigid in certain areas and flexible in proximity to the articulation joint to provide fluid flow communication along the flow path without substantially impairing articulation.
The present invention is particularly advantageous in a medical instrument having an end effector that has multiple motions or operations, Such a medical instrument may comprise a plurality (2, 3 or more) of independent closed hydraulic fluid flow paths extending between the handle portion and the end effector, which each flow path controlling a different operation or movement.
Where the end effector is for stapling tissue, for example, it may have a pair of relatively movable jaws, and a pair of hydraulic actuatorsxe2x80x94one for opening and/or closing the jaws and one for firing the staples. In such an embodiment, a pair of independent closed hydraulic flow paths may extend between the handle and the end effector, and the handle portion may include a separate hydraulic pressure source communicating with each fluid flow path. Each pressure source is controllable by the user for changing the hydraulic pressure within each of the flow paths for selective actuation of the end effector.
In such a medical instrument, the use of flexible hydraulic systems for end effector actuation is of substantial advantage, particularly in combination with multiple articulation joints. The complicated structures and relationships that would be required for direct mechanical control mechanisms through the articulation joints are essentially eliminated, and the instrument fabrication can be greatly simplified and miniaturized.
Although the present invention may be used with a variety of end effectors, tissue stapling is one of its anticipated uses. For tissue stapling, the instrument preferably employs a dual-hydraulic system for controlling the action of the end effector. For example, as a stapler, one closed hydraulic system is employed for opening and/or closing the stapler jaws, and a separate and independent closed hydraulic system is employed to effect the stapling operation.
The end effector preferably includes a plurality of staples carried by one jaw and a staple anvil carried by the other jaw. The staples may be contained in a removable supply cartridge and the hydraulic actuator may be adapted to force the staples from the respective jaw and against the anvil of the other jaw. To effect firing of the staples, the end effector may have a linearly extensible balloon engageable with a movable staple ejector, such as a cam or wedge, to forcibly expel the staples from the jaw upon increase of hydraulic pressure in the balloon. The staples are expelled with enough force to bend over the ends of the staples when they engage against the anvil to clinch tissue that is clamped between the stapler jaws. After the stapling action is complete, the balloon is positively mechanically returned to a retracted or deflated position for the next stapling operation. For purposes of the remainder of this description and any claims, xe2x80x9cballoonxe2x80x9d is intended to be given a broad generic interpretation that comprehends any device expansible under hydraulic pressure, whether a flexible resilient member or otherwise.
To effect opening and closing of the jaws of the end effector, the end effector may include another hydraulic actuator employing a novel piston-cylinder arrangement substantially fully enclosed in the anvil jaw of the end effector. The actuator employs a longitudinally moveable piston and a connecting linkage associated with the piston and cooperative with each of the first and second jaws to move them toward one another upon increase of hydraulic pressure in the hydraulic actuator. Preferably, the jaws are biased to an open position, such as by a spring, and upon the release of hydraulic pressure the jaws would automatically open.
To control jaw clamping, the pressure source in the handle communicating with the jaw closing actuator may be a hydraulic cylinder block communicating with the relevant hydraulic fluid flow path. To change the pressure of the hydraulic fluid, a piston is slidably movable within the cylinder block between at least a higher pressure position and a lower pressure position. The piston may be moved by a lever that is pivotally mounted on the handle portion and engageable with the piston so that operator actuation of the lever directly changes the hydraulic fluid pressure.
The medical instrument may further include a trigger cooperative with one of the pressure sources for changing the hydraulic pressure source in one of the fluid flow paths. As with the lever, the trigger may operate on a piston slidably received in a cylinder block (which may be separate from or one-piece with cylinder block employed by the lever-actuated piston) for changing the pressure in one of the hydraulic flow paths. In a stapling instrument, the trigger may operate to effect the stapling function after the end effector jaws are closed by the lever. A safety latch engageable with the trigger holds the trigger in a lower pressure, retracted and inaccessible position until the jaws are closed and locked in the desired position. The safety may then be released, and the trigger deployed, by a positive deliberate action by the surgeon. When the trigger is pulledxe2x80x94the hydraulic pressure in the fluid flow path is increased, causing the balloon to expand, forcing a wedge or cam forward, and causing staples to be forced from one jaw and against an anvil on the other jaw.
In accordance with a preferred aspect of the present invention, the separate clamping and firing hydraulic systems of the stapler employ a common, one-piece cylinder block. In combination with a unique firing trigger and clamping lever arrangement and piston arrangement, a compact and efficient handle arrangement that is easy to assemble and includes several built-in safety features, as discussed below, is provided.
Other aspects of the present invention, as set forth in the following detailed description and claims, are found in the end effector assembly and in the handle portion alone. Although described in terms of a complete instrument suitable for insertion through a trocar or the like, various features of the present invention found in the end effector and in the handle portion may have application in other instruments and with different style handles and end effectors without departing from the present invention.